We may not preach a crucified Saviour without being also crucified men and women. It is not enough to wear an ornamental cross as a pretty decoration. The cross that Paul speaks about was burned into his very flesh, was branded into his being, and only the Holy Spirit can burn the true cross into our innermost life.
If you can cultivate wholesome mental states prior to sleep and allow them to continue right into sleep without getting distracted, then sleep itself becomes wholesome.